So, probably a stupid question from someone less knowledgeable in electronics. But why hasn't anyone made an all-in-one JVS/JAMMA solution? One piece of hardware that does both JAMMA -> JVS and JVS -> JAMMA?

But why hasn't anyone made an all-in-one JVS/JAMMA solution? One piece of hardware that does both JAMMA -> JVS and JVS -> JAMMA?

for one, they're different enough that you'd basically be building 2 separate devices and cramming them on one board. secondly there's no real point to something like that since for a given cab you'll only ever need conversion from one direction or the other, never both.